At least 21 members of the Syrian security forces were killed on Wednesday at dawn in the region of Aleppo in northern Syria and Harasta, a suburb of Damascus, said the Syrian Observatory for Human Rights (SOHR). "Fifteen members of the security forces, including two officers, were killed at dawn in an ambush on the road to the town of al-Raii," said the SOHR, indicating that the attack was carried out by military dissidents.

SOHR said two army deserters were killed overnight in clashes with soldiers in the same locality.

The Aleppo region has been the target of military operations in recent weeks despite the ceasefire that went into effect last month.

In addition, six soldiers were killed at dawn in clashes in Harasta between the army and defected soldiers, according to opposition activists.

In the province of Deir Ezzor, the armed forces pounded the village of al-Dahla, and in the city of Qouriya, they carried out raids and set homes on fire, reported SOHR.

In the province of Deraa (south), a civilian was killed Wednesday by government forces in the village of Nassib, while heavy gunfire was heard in the town of Dael, said a local source. On Tuesday, violence in Syria killed 34 people, despite the deployment of a small team of UN observers to oversee the fragile cease-fire under the peace plan of the International envoy, Kofi Annan.

The UN chief Ban Ki-moon, and the chief of the observers, General Robert Mood of Norway, called on sides to respect of the ceasefire.